"It's been a very well-flagged, planned succession handover," Mr Clarke said. "He's said to us he'd like to spend all of his time on his philanthropic and other personal investments and commercial interests that he wants to pursue."

The group lifted income from management and performance fees despite volatile market conditions and was buoyed particularly by continuing success of its AHL Diversified hedge fund. The fund generated gross performance fees of $1.05bn, contributing the lion's share of the group's $936m in net performance fees, up from $358m a year ago.

Management fee income climbed to $1.1bn, up about 21pc in proportion with Man's increase in funds under management.

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Man Group management said that while the outlook for financial markets remained uncertain, it had fared well since March as it continued to win investors concerned about volatility in other asset classes. Assets under management have climbed $4bn since the end of March.

"People are giving us money because they are uncertain about what's happening in the world and they want to diversify their portfolio away from what might have historically been skewed towards real estate, shares or private equity investments," Mr Clarke said.

He said the impact of the credit crunch across the marketplace had come as a surprise. "We have had a very long bull market particularly in equities so there was always likely to be a correction at some point, but the suddenness and steepness of it did surprise me."

The dividend total is more than doubled to 44 cents, with the payment of a 24.8 cents final on August 12. The shares jumped 30½ to 619p.